1. Field of the Invention
The present invention relates to a broadcasting system. More particularly, the present invention relates to an apparatus and method for selecting a multi-antenna transmission method in a broadcasting system.
2. Description of the Related Art
With the evolution of communication technologies, next generation broadcasting systems are being developed that support high definition and high transmission capacity. However, next generation broadcasting systems will need to support both a conventional broadcasting standard which requires a high priority bit stream (hereinafter, referred to as HP) having low definition but a high priority and a next generation broadcasting standard requiring a low priority bit stream (hereinafter, referred to as LP) which has a low priority but supports high definition and a high transmission capacity.
The broadcasting system structured as shown in FIG. 1 supports both the HP signal and LP signal. Here, FIG. 1 illustrates a configuration of a broadcasting system defined in a Digital Video Broadcasting (DVB)-Terrestrial (T) standard, which is a European terrestrial broadcasting standard.
FIG. 1 illustrates a configuration of a conventional broadcasting system.
As shown in FIG. 1, a transmission terminal, such as a DVB-Handheld (H) terrestrial channel adapter, of the broadcasting system comprises energy diffusers 100, external coders 102, external interleavers 104, internal coders 106, internal interleavers 108, a modulator 110, a resource allocator 112, an orthogonal frequency division multiplex (OFDM) modulator 114, a digital/analog converter (DAC) 116, a radio frequency (RF) processor 118 and a control signal generator 120. Here, energy diffusers 100 comprise energy diffuser 100-1 and energy diffuser 100-2 which are configured to process the HP signal and LP signal, respectively. The external coders 102 comprise external coder 102-1 and external coder 102-2 which are configured to process the HP signal and LP signal, respectively. The external interleavers 104 comprise external interleaver 104-1 and external interleaver 104-2 which are configured to process the HP signal and LP signal, respectively. The internal coders 106 comprise internal coder 106-1 and internal coder 106-2 which are configured to process the HP signal and the LP signal, respectively.
The energy diffusers 100 evenly distribute energy through a scrambling process so that identical bits cannot be repeated in signals (bit streams) supplied from video coders.
The external coders 102 code the signals supplied from the energy diffusers 100 according to corresponding modulation level to correct errors in the transmission signal.
The external interleavers 104 interleave the signals supplied from the external coders 102 according to a preset rule to prevent burst errors.
The internal coders 106 code the signals supplied from the external interleaver 104 to correct the distributed bit errors of the signals. In this case, the internal coder 106 may use a coding mode identical to or different from that of the external coder 102.
The internal interleaver 108 interleaves the signals supplied from the internal coders 106 bit by bit according to a preset rule. In this case, the internal interleaver 108 combines the LP signal and the HP signal into one stream (signal) and outputs the stream.
The modulator 110 modulates and outputs the signal supplied from the internal interleaver 108 according to corresponding modulation level.
The control signal generator 120 generates a control signal including synchronization channel and resource information for allocating signals to be transmitted. In addition, the control signal generator 120 generates a control signal including transmission parameter signaling (TPS) information. Here, the TPS information represents information for time division to reduce power loss in the broadcasting system. In this case, when performing the time division, the broadcasting system transmits data as shown in FIG. 2.
FIG. 2 illustrates a data transmission mode of a conventional broadcasting system.
As shown in FIG. 2, the broadcasting system transmits a stream as a burst 201 having a high data rate for a short time (burst region 203), and operates in a transmission standby mode for a preset time (off time 205). While the burst bandwidth 207 is relatively high during the burst region 203, the average bandwidth 209 of the time period including burst region 203 and the off time 205 is comparatively low. By operating in this manner, power loss of the broadcasting system is able to be reduced.
As described above, the broadcasting system transmits a stream at a high data rate for a short time and then operates in a transmission standby mode for a preset time, thereby reducing power loss.
The resource allocator 112 allocates the data signal supplied from the modulator 110 and the control signal supplied from the control signal generator 120 to a corresponding resource and outputs the data signal and the control signal.
The OFDM modulator 114 inverse-fast-Fourier transforms the frequency domain signal supplied from the resource allocator 112 to convert it into a time domain signal.
The DAC 116 converts the digital signal supplied from the OFDM modulator 114 into an analog signal and outputs the analog signal.
The RF processor 118 modulates the base-band signal supplied from the DAC 116 into a radio frequency signal and outputs the radio frequency signal.
When using a multi-antenna, the broadcasting system transmits data using independent channels, thereby increasing transmission reliability and data rate without utilizing additional frequency resources or transmission power. For example, the broadcasting system can increase a data rate through a spatial multiplexing using a multi-antenna. Additionally, the broadcasting system can enhance transmission reliability through a diversity method using a multi-antenna.
Accordingly, it is advantageous for a broadcasting system to use a multi-antenna to employ a diversity method to improve reliability of the HP signal and employ a spatial multiplexing method to enhance a data rate of the LP signal.
However, the conventional broadcasting system combines the HP signal and the LP signal into one stream and transmits it. Therefore, the broadcasting system cannot apply different multi-antenna transmission methods to the HP signal and the LP signal. Instead the conventional broadcasting system employs only a single multi-antenna transmission method. That is, even though the broadcasting system uses a multi-antenna, it cannot satisfy both characteristics of the HP signal and LP signal. Therefore, a need exists for an apparatus and method that addresses the issues described above that are associated with the conventional broadcasting system.